U.S. patent number 5,750,055 [Application Number 08/491,017] was granted by the patent office on 1998-05-12 for process for the preparation of industrially applicable difunctional anionic polymerization initiators and their use.
This patent grant is currently assigned to Shell Oil Company. Invention is credited to Frederik Hendrik Van Der Steen, Judith Johanna Berendina Walhof.
United States Patent |
5,750,055 |
Van Der Steen , et
al. |
May 12, 1998 |
Process for the preparation of industrially applicable difunctional
anionic polymerization initiators and their use
Abstract
A process for the preparation of an efficient industrial
organolithium diinitiator, comprising the reaction of two
equivalents of a mono-organolithium initiator with one equivalent
of 1,3-diisopropenyl benzene at a temperature in the range of from
-20.degree. to 60.degree. C., in an apolar hydrocarbon solvent, and
in the presence of a monofunctional tertiary amine in a molar ratio
relative to mono-organolithium initiator from 0.5 to 2, followed by
addition to the reaction mixture of a small amount of conjugated
diene monomer, at a temperature in the range of from 0.degree. to
30.degree. C., to form a solution of an .alpha.,.omega.-dilithio
poly(conjugated diene), having an apparent molecular weight in the
range of from 1000 to 3000.
Inventors: |
Van Der Steen; Frederik Hendrik
(Amsterdam, NL), Walhof; Judith Johanna Berendina
(Amsterdam, NL) |
Assignee: |
Shell Oil Company (Houston,
TX)
|
Family
ID: |
8216992 |
Appl.
No.: |
08/491,017 |
Filed: |
June 15, 1995 |
Foreign Application Priority Data
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|
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Jul 27, 1994 [EP] |
|
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94201847 |
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Current U.S.
Class: |
260/665R |
Current CPC
Class: |
C08F
4/48 (20130101); C08F 36/04 (20130101); C08F
297/042 (20130101); C08F 36/04 (20130101); C08F
4/488 (20130101) |
Current International
Class: |
C08F
36/04 (20060101); C08F 297/00 (20060101); C08F
4/00 (20060101); C08F 297/04 (20060101); C08F
4/48 (20060101); C08F 36/00 (20060101); C07F
001/02 () |
Field of
Search: |
;260/665R |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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185080 |
|
Apr 1982 |
|
EP |
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0316857 |
|
Nov 1988 |
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EP |
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413294 A2 |
|
Aug 1990 |
|
EP |
|
0682041 |
|
Nov 1995 |
|
EP |
|
2313389 |
|
Jun 1975 |
|
FR |
|
Other References
C W. Kamienski, R. C. Morrison and T. L. Rathman, "Difunctional
Lithium Polymerization Initiators". .
R. P. Foss, H. W. Jacobson, H. N. Cripps, and W. H. Sharkey, "Block
and Graft Copolymers of Pivalolactone. 4. Triblock and Block-Graft
Copolymers from Pivalolactone and Isoprene", 1979, American
Chemical Society. .
P. Lutz, E. Franta and Paul Rempp, "An efficient bifunctional
lithium-organic initiator to be used in apolar solvents", 1982,
Polymer. .
T. E. Long, A. D. Broske, D. J. Bradley and J. E. McGrath,
Synthesis and Characterization of Poly (t-Butyl
Methacrylate-b-isoprene-b-t-Butyl Methacrylate) Block Copolymers by
Anionic Techniques, 1989, Journal of Polymer Science. .
L. J. Fetters, C. W. Kamienski, R. C. Morrison, and R. N. Young,
"Remarks on Organodilithium Initiators", 1979, American Chemical
Society. .
R. P. Foss, H.W. Jacobson, and W. H. Sharkey, "A New Difunctional
Anionic Initiator"..
|
Primary Examiner: Shaver; Paul F.
Attorney, Agent or Firm: Haas; Donald F.
Claims
We claim:
1. A process for the preparation of an efficient industrial
organolithium diinitiator, comprising the reaction of two
equivalents of a mono-organolithium initiator with one equivalent
of 1,3-diisopropenyl benzene at a temperature in the range of from
-20.degree. to 60.degree. C., in an apolar hydrocarbon solvent, and
in the presence of a monofunctional tertiary amine in a molar ratio
relative to mono-organolithium initiator from 0.5 to 2, followed by
addition to the reaction mixture of a small amount of conjugated
diene monomer, at a temperature in the range of from 0.degree. to
30.degree. C., to form a solution of an .alpha.,.omega.-dilithio
poly(conjugated diene), having an apparent molecular weight in the
range of from 1000 to 3000.
2. The process according to claim 1, wherein the monofunctional
tertiary amine is used in molar ratio relative to
mono-organolithium initiator from 1.0 to 1.5.
3. The process according to claim 1, wherein the tertiary amine is
a monofunctional amine trialkylamines, the alkyl groups of the
amine containing from 2 to 4 carbon atoms.
4. The process according to claim 3, wherein the amine is
triethylamine.
5. The process according to claim 1, wherein the mono-organolithium
initiator is sec-butyllithium or tert-butyllithium.
6. The process according to claim 5, wherein the initiator is
sec-butyllithium.
7. The process according to claim 1, wherein the reaction
temperature during the reaction of 1,3-diisopropenylbenzene with
the mono-organolithium initiator is in the range of from
-10.degree. to 50.degree. C.
8. The process according to claim 7, wherein the reaction
temperature during the reaction of 1,3-diisopropenylbenzene with
the mono-organolithium initiator is in the range of from 0.degree.
to 30.degree. C.
9. The process according to claim 1, wherein the apolar hydrocarbon
solvent is selected from cycloalkanes having from 5 to 8 carbon
atoms.
10. The process according to claim 9, wherein the apolar solvent is
substantially pure cyclohexane or substantially pure cyclopentane
is used.
Description
FIELD OF THE INVENTION
The present invention relates to a process for the preparation of
industrially applicable difunctional anionic polymerization
initiators and their use for the manufacture of substantially
symmetrical block copolymers derived from at least a conjugated
diene and a monovinylaromatic monomer. More in particular the
present invention relates to a process for the preparation of
.alpha.,.omega.-dilithiopolydienes.
BACKGROUND OF THE INVENTION
Block copolymers of the type ABA or CABAC, wherein B represents a
predominantly poly(conjugated diene)block, A represents a
predominantly poly(monovinylaromatic) block and C represents a
predominantly poly(polar vinyl monomer)block, have shown a growing
interest, while on the other hand the requirements to be met by
such block copolymers with reference to their specified standard
properties have become more and more stringent.
The preparation of dilithium organo compounds for the anionic
polymerization of monovinylaromatic and/or conjugated diene
monomers into block copolymers was known in principle from e.g.
U.S. Pat. Nos. 3,652,516; 3,734,973; 3,663,634; 3,694,516;
3,668,263; 3,903,168; 3,954,894; 4,039,593; 4,172,100; 4,182,818;
4,960,842; European patent applications Nos. 0316857 and 4132294
and from Macromolecules 5, 453-8 (1969); R. P. Foss et al,
Macromolecules 12, 344-6 (1979); C. W. Kamienski et al, Curr. Appl.
Sci. Med. Technol. 315-25 (1985); R. P. Foss et al, Macromolecules
10, 287-291 (1977); R. P. Foss et al, Macromolecules 12, 1210-1216
(1979); Polymer 23, 1953-9 (1982); T. E. Long et al, J. Polym. Sci.
Part A, Polym. Chem. vol. 27, 4001-4012 (1989).
In particular from the U.S. Pat. No. 3,663,634 the preparation of
hydrocarbon soluble organodilithium polymerization initiators was
known. Said preparation comprised intimately contacting lithium
metal with at least one compound selected from the group consisting
of polyaryl substituted ethylenes, hydrocarbon substituted and
unsubstituted conjugated diolefins and vinyl substituted aromatic
compounds containing only carbon and hydrogen atoms, in a solvent
mixture comprising
(A) at least one solvent member selected from the group consisting
of aliphatic, cycloaliphatic and aromatic hydrocarbons, and
(B) at least one solvent member selected from a group of aromatic
ethers, aromatic thioethers and tertiary amines, and wherein the
volume fraction of solvent component (A) in the mixture can range
from 57.0 vol % to 92.0 vol % and wherein the volume fraction of
solvent component (B) in the solvent mixture can range from 8.0 to
43.0 vol %.
As component (B) preferably anisole was proposed and as the
polyaryl-substituted ethylene 1,1-diphenylethylene was
proposed.
The preferred amount of anisole in the solvent mixture was
indicated to be about 15 vol % in combination with 85 vol %
benzene.
From U.S. Pat. No. 3,694,516 was known a method for the preparation
of a solvated lithium metal adduct of at least one member selected
from the group consisting of (a) conjugated polyene hydrocarbon
monomers and in particular 1,3-butadiene or isoprene, (b) vinyl
substituted aromatic hydrocarbon monomers and in particular
styrene, (c) mixtures of (a) and (b), and (d) their slightly
chain-extended oligomers, which comprised providing a solution, in
an organic solvent which includes at least one member selected from
volatile liquid inert strongly solvating dialkyl ethers, cyclic
ethers and tertiary amines, of at least one di- or poly-lithio
adduct selected from the aforesaid (a), (b), (c) and (d) groups,
admixing said solution with at least one member selected from the
group consisting of weakly solvating liquid ethers (e.g. anisole)
and weakly solvating liquid tertiary amines, said weakly solvating
compounds having a boiling point substantially higher than the
boiling point of said strongly solvating compound, and evaporating
from said mixture substantially all of said strongly solvating
compound without substantial evaporation of said weakly solvating
compound. The preferred liquid hydrocarbon solvent was benzene.
In U.S. Pat. No. 4,196,154 multifunctional lithium containing
initiators were lateron disclosed, which were soluble in
hydrocarbon solvents and thus highly useful in the preparation of
block copolymers aimed at.
Additional teachings regarding the use of multifunctional lithium
based initiators could be found in e.g. U.S. Pat. Nos. 4,201,729;
4,200,718; 4,205,016; 4,172,190 and 4,196,153. However, the
disadvantage connected with the use of multifunctional lithium
containing initiators, providing polymers having rather wide
molecular weight distributions (about 1.1 or greater), still
remained.
Additional techniques were proposed, such as the use of
coinitiators such as lithium alkoxides or specific triamines such
as pentamethyldiethylene triamine or combinations thereof were
proposed to obtain butadiene containing block copolymers having
molecular weight distributions down to 1.06. Similar polymers
containing primarily isoprene did not become available at all,
because isoprene appeared to be less easily polymerizable by
anionic techniques compared to butadiene and even rapid polymer
addition did not occur.
It has been generally appreciated by persons skilled in the art,
that block copolymers of improved tensile strength are obtained if
the block copolymer has a reduced molecular weight distribution. In
particular, a triblock polymer of the formula styrene/isoprene/
styrene prepared by conventional coupling of monofunctional lithium
initiated diblock copolymers was found to demonstrate significantly
improved tensile strength for equivalent number average molecular
weight polymers, if the molecular weight distribution (Mw/Mn) is
1.03 instead of 1.20, L. C. Case, Makromol. Chem. V. 37, p 243
(1960).
Therefore there is still a need for block copolymers of
monovinylaromatic monomer and conjugated diene, having the
presently required physical properties and hence a related
appropriate molecular weight distribution.
According to the disclosure of the European patent application No.
0316.857 it was tried to produce the block copolymers aimed at by
means of a process, using a specific diinitiator organo-lithium
compound and a specific organic diamine or triamine, optionally
combined with a metal alkoxide having from 2 to 16 carbon
atoms.
From the European patent application No. 0413.294 it was known to
produce narrow molecular weight distribution block copolymers
(Mw/Mn in the range from 1.027 to 1.058) of the formula
B-B'-X-(B'-B) or A-B-B'-X-(-B'BA) wherein A was a block of a non
elastomeric monomer, B is a block of isoprene, B' is a block of
butadiene and X is the remnant of a hydrocarbon soluble
difunctional lithium initiator, said block copolymer having a
molecular weight distribution (Mw/Mn) of less than 1.06.
As specific difunctional lithium based initiator were mentioned
1,3- or 1,4-phenylene bis(3-methyl-1-phenylpentylidene) bislithium
or 1,3- or 1,4-phenylene
bis(3-methyl-1-(4-methyl)phenyl-pentyliydene) bislithium.
Moreover the polymerization was conducted in the presence of an
aliphatic triamine and in particular N,N,N',N",N"-pentamethyl
diethylene triamine.
It will be appreciated that especially from both before mentioned
European patent publications there was a teaching to a person
skilled in the art to use multifuntional amines during the
polymerization of the block copolymers aimed at.
Although the use of dilithio initiators for the preparation of
symmetrical block copolymers having an appropriate narrow molecular
weight distribution had been disclosed in principle for a long
time, up to now no actual commercial polymerization process has
been carried out with the use of said initiators, due to an
inevitably occurring too high vinyl content in the poly(conjugated
diene) blocks caused by the copresence of a polar compound such as
amines or ethers.
It will be appreciated that symmetrical block copolymers aimed at,
can in principle be manufactured by coupling of living initially
prepared intermediate block copolymers with a multifunctional and
in particular difunctional coupling agent.
However a disadvantage of such coupling process was formed by the
presence in the final block copolymer of a usually difficultly
controllable amount of diblock copolymer, formed from the
intermediate living polymer.
Another alternative preparation route of such symmetrical block
copolymers comprises the fully sequential polymerization by using a
monofunctional organolithium initiator optionally in combination
with a second initiation to provide a predetermined controlled
amount of diblock copolymer.
However, a problem of said full sequential polymerization process
is caused by a relatively broad molecular weight distribution of
the block segment, due to a relatively difficult initiation of the
last monomer charge and a difficult control of the molecular weight
of the last block.
It will be appreciated that an industrial process for the
preparation of symmetrical block copolymers, and in particular
symmetrical triblock copolymers, which show an acceptable molecular
weight distribution in combination with a relatively low vinyl
content in the poly(conjugated diene) blocks due to 1,2 or 3,4
polymerization, which could meet the requirements of modern end
uses of said block copolymers, by the use of a difunctional
organolithium initiator, may provide significant advantages such as
shorter polymerization times.
An object of the present invention was therefore to provide a
suitable difunctional organolithium initiator. Additional objects
of the present invention was to provide an attractive industrial
process for the preparation of symmetrical block copolymers as
specified hereinbefore and to provide a process for the preparation
of such initiators.
As a result of extensive research and experimentation such a
difunctional organolithium initiator aimed at was surprisingly
found.
SUMMARY OF THE INVENTION
The present invention is a process for the preparation of an
efficient industrial organolithium diinitiator, comprising the
reaction of two equivalents of a mono-organolithium initiator with
one equivalent of 1,3-diisopropenylbenzene at a temperature in the
range of from -20.degree. to 60.degree. C. in an apolar hydrocarbon
solvent, and in the presence of a monofunctional tertiary amine in
a molar ratio relative to mono-organolithium initiator of from 0.5
to 2 and more preferably from 1.0 to 1.5, followed by addition to
the reaction mixture of a small amount of conjugated diene monomer,
at a temperature in the range of from 0.degree. to 30.degree. C.,
to form a solution of an .alpha.,.omega.-dilithio poly(conjugated
diene), having an apparent molecular weight in the range of from
1000 to 3000.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is a process for the preparation of an
efficient industrial organolithium diinitiator, comprising the
reaction of two equivalents of a mono-organolithium initiator with
one equivalent 1,3-diisopropenylbenzene at a temperature in the
range of from -20.degree. to 60.degree. C. in an apolar hydrocarbon
solvent, and in the presence of a monofunctional tertiary amine in
a molar ratio relative to mono-organolithium initiator of from 0.5
to 2 and more preferably from 1.0 to 1.5, followed by addition to
the reaction mixture of a small amount of conjugated diene monomer,
at a temperature in the range of from 0.degree. to 30.degree. C.,
to form a solution of an .alpha.,.omega.-dilithio poly(conjugated
diene), having an apparent molecular weight in the range of from
1000 to 3000.
As mono-organolithium initiator is preferably used sec.butyllithium
or tert.butyllithium, the former of which is most preferred.
The reaction temperature during the reaction of
1,3-diisopropenylbenzene with the monoorganolithium initiator is
preferably in the range of from -10.degree. to 50 .sub.-- C. and
more preferably in the range of from 0.degree. to 30 .sub.-- C.
The apolar hydrocarbon solvent was found to be preferably selected
from cycloalkanes, having from 5 to 8 carbon atoms and more
preferably having 5 or 6 carbon atoms.
Also mixtures of such cycloalkanes or mixtures of predominant
amounts of such cycloalkanes and minor amounts of aliphatic
hydrocarbons having from 5 to 8 carbon atoms can be used, but the
use of substantially pure cyclohexane or substantially pure
cyclopentane was found to be most preferred.
The conjugated diene monomer to be added in small amounts to the
reaction medium can be selected from butadiene, isoprene,
2-ethyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene and
1,3-pentadiene or mixtures thereof.
As the conjugated diene is preferably used the same conjugated
diene as those which constitute later on the poly(conjugated diene)
block(s) in the final block copolymer.
The apparent molecular weight of the prepared
.alpha.,.omega.-dilithio initiator is preferably in the range of
from 1000 to 2800 and more preferably from 1200 to 2300.
Said apparent molecular weight is a number average molecular weight
determined by gel permeation chromatography using polystyrene
standard calibration polymers.
It was surprisingly found that stable, hydrocarbon solvent soluble
.alpha.,.omega.-dilithio initiators could be obtained by addition
of a small amount of a conjugated diene monomer and a specific
amount of monofunctional tertiary amine relative to the amount of
monolithium compound which appeared to influence the
stereochemistry of the diene polymerization in an acceptable
minimal degree during the subsequent use of the initiator for the
preparation of the final block copolymer (vinyl content was found
to be at most 10%).
Suitable examples of monofunctional amines to be used for the
preparation of the diinitiator of present invention are
trialkylamines, the alkyl groups in which containing from 1 to 5
carbon atoms and more preferably from 2 to 4 carbon atoms,
triarylamines or tri(aralkyl)amines. Most preferably triethylamine
is used.
It will be appreciated that another aspect of the present invention
is formed by the reaction product solutions, comprising the stable
.alpha.,.omega.-dilithio initiator obtained according to the
hereinbefore specified process, dissolved in the hydrocarbon
solvent as such or optionally diluted with the hereinbefore
specified hydrocarbon solvent(s) to achieve the desired
concentration of the .alpha.,.omega.-dilithio initiator prepared,
to which have been optionally added one or more of the monomers to
be incorporated into the finally desired block copolymers.
A further aspect of the present invention is formed by a process
for the preparation of symmetrical block copolymers derived from
monovinylaromatic monomers, conjugated dienes and optionally
additional polar vinyl monomers having the required combination of
narrow molecular weight distribution (Mw/Mn.ltoreq.1.20) and
relatively low vinyl content (.ltoreq.10%) of the predominantly
poly(conjugated diene) blocks, by anionic polymerization, using the
hereinbefore specified .alpha.,.omega.-dilithio initiator
solution.
More in particular a process is provided for the preparation of
linear block copolymers constituted by monovinylaromatic monomer,
conjugated diene and optionally a polar vinyl monomer of the
structure ABA, ABCBA, CBC, ACBCA or CABAC respectively, wherein A
represents a predominantly poly(monovinylaromatic) block, B
represents a predominantly poly(conjugated diene) block and C
represents a predominantly poly(polar vinyl) block.
Accordingly the present invention is also relating to a process,
comprising:
(1) charging a predominantly conjugated diene monomer as specified
hereinbefore to an .alpha.,.omega.-dilithio initiator in a
hereinbefore specified hydrocarbon solvent and allowing essentially
complete polymerization to occur; thereafter
(2) optional addition of an ether to promote the cross-over and
charging a predominantly monovinylaromatic monomer or a
predominantly polar vinyl monomer after introduction of an
end-capping agent and addition of ether and allowing essentially
complete polymerization to occur; and optionally
(3) introduction of a reagent for introduction of an end-capping of
the living polymers and introduction of an ether and charging a
predominantly polar vinyl monomer, and allowing essentially
complete polymerization.
With the terms "predominantly conjugated diene", "predominantly
conjugated diene" and "predominantly polar vinyl compound" as used
throughout this specification, is meant that the indicated monomer
may be substantially pure or mixed in a minor degree with a
structurally related monomer or with a structurally different
monomer and preferably the same comonomer, which occurs in other
block segments, i.e. in amounts of less than 15 mol % of the total
monomers of said blocks and preferably less than 5 mol %.
Suitable examples of monomer mixtures constituting the blocks A are
mixtures of styrene and minor amounts of monomers selected from the
group consisting of alpha-methylstyrene, p-vinyltoluene, m-vinyl
toluene, o-vinyltoluene, 4-ethylstyrene, 3-ethylstyrene,
2-ethylstyrene, 4-tert.butylstyrene, 2,4-dimethylstyrene, 2 or
4-vinylpyridine butadiene, isoprene, 2-ethyl-1,3-butadiene,
2,3-dimethyl-1,3-butadiene and 1,3-pentadiene or mixtures
thereof.
Suitable examples of monomer mixtures constituting block B are
mixtures of isoprene or butadiene and minor amounts of monomers
selected from styrene, alpha-methylstyrene, p-vinyltoluene,
m-vinyltoluene, o-vinyltoluene, 4-ethylstyrene, 3-ethylstyrene,
2-ethylstyrene, 4-tert.butylstyrene, 2,4-dimethylstyrene, butadiene
or isoprene, 2-ethyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene and
1,3-pentadiene or mixtures thereof.
Preferably the constituting monomers of blocks A are mixtures of
styrene in a major amount and structurally related monomers as
specified hereinbefore in a minor amount and preferably
alpha-methylstyrene, while the constituting monomers of block B are
selected from butadiene, isoprene and mixtures thereof.
Suitable examples of monomer mixtures constituting optional blocks
C are mixtures of a major component selected from lower alkyl
(C.sub.1 -C.sub.4) esters of acrylic acid or methacrylic acid such
as tert.butylacrylate, tert.butylmethacrylate, methylacrylate,
methylmethacrylate, or esters or anhydrides of maleic acid, fumaric
acid, itaconic acid, cis-4-cyclohexene-1,2-dicarboxylic acid,
endo-cis-bicyclo(2,2,1)-5-heptene-2,3-dicarboxylic acid or mixtures
thereof, 2- or 4-vinylpyridine and as a minor component a comonomer
selected from styrene, alpha-methylstyrene, p-vinyltoluene,
m-vinyltoluene, o-vinyltoluene, 4-ethylstyrene, 3-ethylstyrene,
2-ethylstyrene, 4-tert.butylstyrene, 2,4-dimethylstyrene, butadiene
or isoprene, 2-ethyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene and
1,3-pentadiene or mixtures thereof.
Most preferably the blocks A, B and C are constituted by one
substantially pure monomer.
Suitable examples of cross-over ethers are THF, dioxo,
diethoxypropane, glyme, diglyme and the like. Diethoxypropane is
the most preferred.
It will be appreciated that according to a preferred process
embodiment, the main solvent used for initial preparation of
.alpha.,.omega.-dilithio initiator and the main solvent used during
the actual block copolymer polymerization is the same, although it
is not strictly necessary.
Suitable examples of ethers to be used as cosolvent for the
polymerization of the polar vinyl monomers are diethylether, THF,
tert-butylmethylether, diisopropylether and the like.
A further aspect of the present invention is formed by the block
copolymers, obtained by the hereinbefore specified process and
characterized by the combination of a narrow molecular weight
distribution (Mw/Mn.ltoreq.1.20) and a relatively low vinyl content
of the predominantly poly(conjugated diene)blocks
(.ltoreq.10%).
Preferred block copolymers according to the present invention are
linear triblock or five block copolymers derived from styrene,
butadiene or isoprene and/or a lower alkyl ester of acrylic acid or
methacrylic acid, or 2- or 4-vinylpyridine respectively as pure
block constituents.
The invention is illustrated by the following examples, however,
without any restriction of the scope of it to these specific
embodiments.
EXAMPLE 1
Reaction of BuLi With 1,3-Diisopropenyl Benzene
Procedure A
To a stirred vessel, containing 80 ml of dry cyclohexane 0.65 g
(6.4 mmoles) of triethylamine were added. Subsequently, 6.3 mmoles
of s-BuLi (3.6 g of a 12 wt % solution in hexanes) and 0.48 g (3
mmoles) of 1,3-diisopropenylbenzene were added at room temperature.
The reaction was continued for 35 minutes at room temperature,
leading to a dark red solution.
Procedure B
To a stirred vessel, containing 200 ml of dry cyclohexane, 0.61 g
(6 mmoles) of triethylamine were added. Subsequently, 6 mmoles of
t-BuLi (5 ml of a 1.2 Molar solution in hexanes) and 0.48 g (3
mmoles) of 1,3-diisopropenylbenzene were added at 0.degree. C. The
reaction was continued for 1 hour.
EXAMPLE 2
Preparation of .alpha.,.omega.-Dilithiopolybutadiene
Procedure A
To the solution obtained by procedure A of Example 1 4.6 g of
butadiene were added at 0.degree. C. The dark red color rapidly
changes to a light orange and becomes pale yellow after stirring
overnight at room temperature. This solution was used as stock for
polymerization experiments with a concentration of
.alpha.,.omega.-dilithiopolybutadiene (MW=1350) of 0.025 Molar.
Procedure B
To the solution obtained by procedure B of Example 1 5.8 g of
butadiene were added at 0.degree. C. The dark red color rapidly
changes to a light orange and becomes pale yellow after stirring
overnight. This solution was used as stock for polymerization
experiments with a concentration of
.alpha.,.omega.-dilithiopolybutadiene (MW=2100) of 0.015 Molar.
EXAMPLE 3
Synthesis of SBS Block Copolymers With
.alpha.,.omega.-Dilithiopolybutadiene A Using Diethoxypropane as
Promotor For the Cross-Over to Styrene Polymerization
To a polymerization bottle, charged with 250 ml of dry cyclohexane,
a few drops of .alpha.,.omega.-dilithiopolybutadiene A were added
to titrate the solution. Thereafter the reactor was charged with
11.2 g of butadiene and 6 ml of solution A (containing 0.15 mmol
diinitiator) at room temperature. Polymerization was carried out
for 2 hours at 60.degree. C. A sample was withdrawn for analysis.
The polybutadiene has the following characteristics: MW 78000
g/mol, Mw/Mn=1.18 and a vinyl content of 9.2%. To the bottle
reactor were then added 25 .mu.L (100 ppm) of diethoxypropane and
5.4 g of styrene and polymerization was continued for 30 minutes at
60.degree. C. To the solution 1 ml of ethanol was added to
terminate the polymerization. The recovered triblock copolymer was
stabilized with antioxidant and had the following characteristics:
MW 97000 g/mol, Mw/Mn=1.19. A sample was subjected to ozonolysis to
leave PS with MW 20000 g/mol.
EXAMPLES 4-5
Following the procedure of Example 3, two other SBS triblock
copolymers were prepared with the characteristics as shown in Table
I.
______________________________________ vinyl MW PS Sample MW PB MW
PS.sup.a M.sub.w /M.sub.n % (ozon)
______________________________________ 4 84000 15000 1.19 9.2 16000
5 81000 21000 1.21 9.2 21500 ______________________________________
.sup.a Calculated from GPC and .sup.1 H NMR, assuming a triblock
structure.
EXAMPLE 6
Synthesis of SIS Block Copolymers With
.alpha.,.omega.-Dilithiopolybutadiene A Using Diethoxypropane as
Promotor For the Cross-Over to Styrene Polymerization
To a polymerization bottle, charged with 250 ml of dry cyclohexane
a few drops of .alpha.,.omega.-dilithiopolybutadiene A were added
to titrate the solution. Thereafter the reactor was charged with
14.7 g of polyisoprene and 6 ml of solution A (containing 0.15 mmol
diinitiator) at room temperature. Polymerization was carried out
for 90 minutes at 60.degree. C. A sample was withdrawn for
analysis. The polyisoprene has the following characteristics: MW
114000 g/mol, Mw/Mn=1.17 with a 3,4 content of 4.6%. To the bottle
were then added 25 .mu.L (100 ppm) of diethoxypropane and 3.4 g of
styrene and polymerization was continued for 30 minutes at
60.degree. C. To the solution was added 1 ml of ethanol to
terminate the polymerization. The recovered triblock copolymer was
stabilized with antioxidant and had the following characteristics:
MW 133000 g/mol, Mw/Mn=1.25. A sample was subjected to ozonolysis
to leave PS with MW 12000 g/mol.
EXAMPLE 7
Synthesis of SBS Block Copolymer With
.alpha.,.omega.-Dilithiopolybutadiene B With THF as Promotor For
the Cross-Over to Styrene Polymerization
To a reactor, charged with 1 1 of dry cyclohexane, were added a few
drops of .alpha.,.omega.-dilithiopolybutadiene B to titrate the
solution. Thereafter the reactor was charged with 30 g of butadiene
and 40 ml of solution B (containing 0.6 mmol diinitiator) at room
temperature. The temperature was allowed to rise to 40.degree. C
and polymerization continued for 10 hours at 40.degree. C. A sample
was withdrawn for analysis. The polybutadiene has the following
characteristics: MW 51000 g/mol, Mw/Mn=1.06 and a vinyl content of
15%. To the reactor were then added 50 .mu.L of dry THF and 20 g of
styrene and polymerization was continued for 2 hours at 40.degree.
C. To the solution was added 1 ml of methanol to terminate the
polymerization. The recovered triblock copolymer was stabilized
with antioxidant and had the following characteristics: MW 89000
g/mol, Mw/Mn=1.07.
A solvent-casted had a Tensile Strength of 30.5 MPA and an
Elongation at break of 1500%.
EXAMPLE 8
Synthesis of SBS Block Copolymers With
.alpha.,.omega.-Dilithiopolybutadiene A Without Promotor for the
Cross-Over to Styrene Polymerization
To a polymerization bottle, charged with 250 ml of dry cyclohexane,
a few drops of .alpha.,.omega.-dilithiopolybutadiene A were added
to titrate the solution. Thereafter the reactor was charged with
8.6 g of butadiene and 6.8 ml of solution A (containing 0.17 mmol
diinitiator) at room temperature. Polymerization was carried out
for 2 hours at 60.degree. C. A sample was withdrawn for analysis.
The polybutadiene has the following characteristics: MW 52000
g/mol, Mw/Mn=1.24 and a vinyl content of 8.5%. To the bottle
reactor were then added 5.5 g of styrene and polymerization was
continued for 45 minutes at 60.degree. C. To the solution was added
1 ml of ethanol to terminate the polymerization. The recovered
triblock copolymer was stabilized with antioxidant and had the
following characteristics: MW 90000 g/mol, Mw/Mn=1.19. A sample was
subjected to ozonolysis to leave PS with MW 21500 g/mol.
COMPARATIVE EXAMPLES
EXAMPLES 9-12
Inefficiency of the s-BuLi/1,3-DIB Adduct
The adduct of s-BuLi and 1,3-diisopropenylbenzene was prepared
following the procedure A of Example 1. With the resulting
solution, several polymerizations have been carried out as shown in
Table II.
______________________________________ Tensile Elong Sample MW PB
MW PS.sup.a M.sub.w /M.sub.n (MPA) (%) PS(ozo)
______________________________________ 9 10000 18000 1.30 too --
40000 weak 10 20000 18000 1.30 too -- 45000 weak 11 55000 25000
1.25 too -- 45000 weak 12 70000 13000 1.20 0.6 200 30000
______________________________________ .sup.a Calculated from GPC
and .sup.1 H NMR, assuming a triblock structure.
* * * * *